1. Field of the Invention
This invention relates in general to contour tracing apparatus and more particularly to improved and more economical contour tracing apparatus.
2. Description of the Prior Art
Contour tracing apparatus incorporates a tracing or scanning head which usually includes a plurality of photocells to sense a drawing line or pattern edge, hereinafter referred to as a contour. The photocells control the angular orientation of a steering head motor. The angular orientation of the steering head motor in turn controls the angular position of the photocells together with a resolver. The resolver in turn controls the relative speed of a pair of coordinate drive motors. The coordinate drive motors move the head through a respective gear and rack along the contour while one or more cutting torches, for example, moved with the head by the coordinate drive motors, cut a work-piece in a pattern corresponding to the contour.
The coordinate drive motors are each usually pivotally supported on a shaft rotatably supported in expensive spaced bearings located in a pair of spaced expensive bracket arms. The load creates a bending moment on the shaft and the arrangement provides inadequate support against backlash between the gear and rack.
The steering head is also expensive since it utilizes a complicated, large, cast metal housing to accommodate the parts, together with a kerf or tool offset adjustment comprising a rack and gear arrangement and either expensive lens or lamp arrangements.